1. Field of the Invention
This invention relates to a method for producing permanent magnet alloy particles of a rare earth element containing permanent magnet alloy, which particles are suitable for use in producing bonded permanent magnets.
2. Description of the Prior Art
In various electrical applications, such as in electric motors, it is known to use bonded permanent magnets. Bonded permanent magnets are constructed of a dispersion of permanent magnet alloy particles in a bonding non-magnetic matrix of for example plastic. The permanent magnet particles are dispersed in the bonding matrix and the matrix is permitted to cure and harden either with or without magnetically orienting the dispersed particles therein.
Magnet alloys of at least one rare earth element, iron and boron are known to exhibit excellent energy product per unit volume and thus it is desirable to use these alloys in bonded magnets where low cost, high plasticity and good magnetic properties are required. It is likewise known with respect to these permanent magnet alloys that comminuting of these alloys to produce the fine particles required in the production of bonded magnets results in a significant decrease in the intrinsic coercivity of the alloy to a level wherein the particles are not suitable for use in producing bonded magnets. Hence, it is not possible to produce particles of these alloys for use in the production of bonded permanent magnets by comminuting castings of the alloy.
It is known to produce permanent magnet alloys of these compositions in particle form by inert gas atomization of a prealloyed melt of the alloy. The as-atomized particles, however, do not have sufficient intrinsic coercivity for use in producing bonded permanent magnets.